Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J1/00—Pistons; Trunk pistons; Plungers
  • F16J1/10—Connection to driving members
  • F16J1/14—Connection to driving members with connecting-rods, i.e. pivotal connections
  • F16J1/16—Connection to driving members with connecting-rods, i.e. pivotal connections with gudgeon-pin; Gudgeon-pins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
  • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
  • B23P15/10—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass pistons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
  • F02F3/00—Pistons 

Definitions

• the present invention relates to pistons for
• Pistons for gasoline and diesel engines usually have a shaped hole in the piston hub to prevent excessive
• a conically cut hub is usually used, i.e. the lower hub length is shorter than the upper hub length (in the present case the lower side denotes the side which is away from the piston crown, while the upper side is the side which is directed towards the piston crown).
• the piston hub is realized in the prior art as a continuous bore in order to ensure the coaxiality of the two hub sides.
• the corresponding form drilling is carried out by turning, with conventional Lathes the lower hub shape must correspond to the upper one, ie the hub surface is formed by rotating a profile curve around the bore axis and a cut perpendicular to the bore axis results in a circular shape with a radius defined by the profile curve. Due to the
• Piston hub differs. Since the design of the piston hub is carried out primarily for reasons of strength under ignition pressure, the lower piston hub can be under
• Centrifugal load is a critical load on the edge
• the deflection can be variably defined depending on the angle. In principle, this makes it possible to close non-rotationally symmetrical shaped bores
• the invention aims to reduce the disadvantages mentioned.
• a piston for an internal combustion engine has two piston hubs.
• Such a piston can be a piston for diesel engines, but also for gasoline engines.
• the piston hubs are those parts of the piston which are designed to receive a piston pin and which are used when such a piston pin is used
• Piston connect the piston to the connecting rod.
• Piston hubs are essentially constant
• Piston hubs in the part in which they receive the piston pin have a cross section that does not widen or narrow significantly or change in any other way in the direction of the piston hub.
• This essentially constant cross-section does not have to extend through the entire piston hub - it is sufficient if this essentially constant cross-section only extends over the area through which the piston pin is received and held when the piston is used.
• such a piston is essentially cylindrical and has an axis which extends along the axis of the cylinder. A plane perpendicular to this axis is defined as the reference plane of the piston.
• the center lines of the piston hubs are inclined with respect to the reference plane.
• the center lines of the piston hub are understood to mean a line which is defined by those parts of the piston hub which have a substantially constant cross section.
• the inclination of the center lines is preferably such that the piston hubs are inclined away from the piston crown when moving away from the piston crown
• Center lines of the piston hubs with respect to the reference plane are in the range from 0.02 ° to 1 °, particularly preferably in the range from 0.02 ° to 0.5 °. Simulations have shown the suitability of this angular range.
• the invention is intended for all types of pistons, i.e. both petrol pistons and diesel pistons.
• the primary pistons i.e. both petrol pistons and diesel pistons.
• diesel pistons which typically consist of steel or an aluminum alloy
• the two center lines of the two piston hubs enclose the same angle with the reference plane.
• center lines of the two piston hubs are mirror-symmetrical to one another with respect to a plane that contains the axis of the piston.
• this plane would be a plane that extends centrally between the two piston hubs and is perpendicular to the two piston hubs.
• the piston hubs have an oval profile in cross section. With such an oval profile, the stress that occurs in the piston can be reduced, which for the
• a piston according to the invention for an internal combustion engine is defined in a coordinate system KSo as follows:
• the axis z 0 corresponds to the axis of a piston
• Piston crown The axis x 0 points in the direction of the pressure side, the axis y0 points in the direction of the front side.
• the bolt plane be defined, which is displaced parallel to the y 0 z 0 plane by a dimension d, the bolt offset, in the x 0 direction.
• the xoyo _ plane is referred to as the eye plane (hub plane), the xo z o plane as the running plane.
• Piston hub Two points A and B are defined on this straight line, each of which is half the length of the bolt from the running plane. These points mark the end of the piston hub and the beginning of the grooves for the
• Coordinate system KS 1 , KS 2 defined, with the z-axis pointing from A or B to C and the r-axis lying in the bolt plane and pointing towards the piston crown.
• Edge stress on the lower piston hub can be excluded.
• a profile hole is defined in the interval [0, L B ], where L B defines the length of the bolt hole.
• the profile bore runs from the starting points of the two bolt bores A and B in direction C and defines the local radial expansion R as a continuous and convex function f of the axial deflection:
• z 1 , z 2 define the respective positions along the respective hub axis.
• R denotes the distance of the respective hub surface from the line AC or BC.
• a piston can be manufactured according to one of the preceding claims.
• a piston blank is arranged on a turntable.
• Such a piston blank is an object from which the finished piston is to be produced.
• the piston blank is machined from one side of the blank (a shell side in the finished piston) (for example, by turning) to form one of the two piston hubs. Then the
• Piston blank rotated around the axis of the piston to be manufactured (typically by 180 °). Then he will be on one machined second position from the outside in to form the second of the two piston hubs. Since only one device for machining the piston blank has to be provided, such a method is easier to implement.
• a piston blank on a platform which can be pivoted about a pivot axis which is perpendicular to the axis of the piston to be manufactured and to the straight line which connects the two piston hubs in the finished piston.
• a first step of machining the first of the two piston hubs is formed, for which purpose the piston blank is rotated through the angle about the pivot axis. This erosion machining takes place essentially along the direction which extends along the straight line which connects the two piston hubs in the finished piston.
• This erosion machining also takes place essentially along the direction in which the erosion machining was carried out during the first step. I.e. the direction in which it is removed does not differ apart from the pivoting angle a between the production of the first piston hub and the second piston hub.
• Such a method is easy to implement, but a corresponding “long” tool is required for the machining.
• the pivoting takes place through an angle of ⁇ , i.e. the angle of inclination of the piston hubs in relation to the
• Another manufacturing method according to the invention comprises arranging the piston blank on a platform. However, this can be moved along the axis of the piston to be manufactured. The piston blank is then removed in machined in a direction perpendicular to the axis of the piston to be manufactured to form one of the two piston hubs.
• the piston blank is moved along the axis of the piston to be manufactured in order to obtain a first one
• the invention is also achieved by a device which is designed to carry out a method according to one of claims 9-11.
• Fig. 1 shows a piston according to the invention in a
• Fig. 2 shows a piston according to the invention in a
• Fig. 3 shows the piston of Figure 2 in another
• Fig. 4 shows a piston from the prior art in
• Fig. 5 shows the warm play of a piston according to the prior art.
• 6 + 7 show the upper and lower shaped bores of a first piston according to the invention in the cold state (FIG. 6) and in the operating state (FIG. 7), each minus cold or warm play.
• FIG. 12 shows a third embodiment of a method for producing a piston according to an embodiment of the invention.
• Figure 1 shows an overall view of a piston according to the invention. This piston is also shown in sectional views in Figures 2 and 3.
• the piston 100 has a piston head 110, which at
• This piston typically has ring grooves which can accommodate piston rings.
• piston hubs 120 which are designed to receive a piston pin (not shown).
• these piston hubs each have grooves 130 on their radial ends, which are used for receiving serve of retaining rings that hold the piston pin in the piston hub 120.
• FIG. 3 indicates how the piston hubs are to be pivoted with respect to the horizontal.
• Piston hub extends along the straight line that connects points A and B.
• Points A and B indicate the centers of the cross sections through the piston hub at the points at which the inner edges of the grooves for the locking rings are located.
• each individual piston hub is inclined downward with respect to this line, as is indicated by lines g 1 and g2.
• Such a design of the piston hub can by a
• the inclination angle is typically significantly less than 1 °.
• the bolt can continue to be mounted on the inside of the expanding bore and the play between the bolt and the hub, although the axes of the hub are no longer arranged coaxially, as is customary in the prior art.
• FIGS. 4 to 5 shows a finite (heavily oversubscribed, oversubscription factor 50)
• FIGS. 6 and 7 show the profile of a piston hub in the cold state (FIG. 6) and operating state (FIG. 7) of a piston according to the invention.
• the operating state is understood to mean the temperatures which occur in the engine when such a piston is used.
• the upper solid line shows the top of the piston hub, and the lower solid line shows the bottom of the
• Piston hub The dashed line denotes the axis of the hub.
• Figure 7 shows the same in operating condition, i.e. at those temperatures that occur in the operating state. It can be clearly seen that in particular the axis in the
• Operating state runs parallel to the X-axis and that voltages are thus avoided.
• FIGs 10-12 schematically show manufacturing processes for pistons according to the invention.
• a piston blank 150 on a turntable (not shown) is arranged.
• a piston hub 120 ' is produced by means of an inclined feed movement V of an abrasive tool. After the piston hub 120 'has been formed, the blank 150 is rotated through 180 ° (rotation D). Then the second piston hub is manufactured using the same abrasive
• Figure 11 shows a second embodiment of the invention.
• a piston blank 160 is arranged on a pivotable platform (not shown).
• the platform is first tilted by a tilt angle and a piston hub 120 'is produced by a machining V.
• tilt movement K After the first piston hub 120 'has been formed, the piston is tilted back by a tilt angle -2a (tilting movement K).
• the second piston hub 120 ′′ is then produced.
• FIG. 12 shows a third method according to the invention for producing a piston.
• a piston blank 160 is arranged on a platform, not shown, and a piston hub 120 'is formed by means of a machining V, while the piston blank along a
• Travel direction F is shifted.
• the machining is carried out completely horizontally.
• the piston is then machined in the same direction of removal V in order to remove the second piston hub 120 ′′.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Pistons, Piston Rings, And Cylinders (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=68318897

Family Applications (1)

Country Status (4)

Family Cites Families (19)

• 2018
  • 2018-10-26 DE DE102018218373.2A patent/DE102018218373A1/de active Pending
• 2019
  • 2019-10-22 WO PCT/EP2019/078682 patent/WO2020083885A1/de unknown
  • 2019-10-22 CN CN201980068100.9A patent/CN112867882A/zh active Pending
  • 2019-10-22 EP EP19791243.9A patent/EP3870883A1/de active Pending

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